JP2008128811A - Defect inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently perform inspection using light emitted from a substrate in a plurality of angle directions, in a defect inspection device. <P>SOLUTION: The defect inspection device comprises a moving stage 13 for mounting the substrate 21 and relatively moving it in the direction orthogonal to the longitudinal direction of an illumination area L, a first illumination section 10, second illumination section 11, and third illumination section 12 for emitting illumination light to the illumination area L, an image-formation optical system 25 for image-forming the light from the illumination area L, a one-dimensional imaging section 27 for acquiring an image of the substrate 21, and an angle setting section for setting the incident angle of the illumination light from each illumination section at a mutually different angle. Each illumination section emits a light of a different wavelength as an illumination light. The one-dimensional imaging section 27 comprises dichroic mirrors 30 and 31 for selecting the light of mutually different wavelength, and a first light receiving section 201, a second light receiving section 202, and a third light receiving section 203 for receiving the light of the selected wavelength. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a defect inspection apparatus that mainly inspects a surface of a substrate on which a periodic pattern is formed as an object. For example, the present invention relates to a defect inspection apparatus such as a semiconductor wafer or a liquid crystal substrate.

An integrated circuit is formed on a semiconductor wafer (hereinafter referred to as a wafer) by stacking a plurality of periodic patterns. In the photolithography process, a resist film is applied to the wafer, the pattern is exposed, and the pattern is formed by etching. If dust adheres, scratches, resist film unevenness, exposure failure, or the like occurs on the wafer in the process, the pattern becomes defective and the integrated circuit does not operate normally. Therefore, it is necessary to verify the presence or absence of such defects before etching.
Conventionally, a defect inspection apparatus for inspecting the presence or absence of defects acquires image information of a substrate using specularly reflected light, diffracted light, scattered light, etc. from the substrate in order to detect various defects generated on the substrate, What is inspected is known. FIG. 4 shows a configuration diagram of an example of a conventional defect inspection apparatus.
The substrate 210 can be moved in the direction of an arrow by a stage (not shown), and an illumination unit 220 that irradiates linear illumination light in a direction orthogonal to the movement direction is arranged from the direction of the incident angle θ _i . The substrate 210 is illuminated. The light from the substrate 210 is imaged by the imaging optical system 250 including the collimating lens 230 and the imaging lens 240 arranged in the direction of the emission angle θ _o , and the one-dimensional image is acquired by the one-dimensional imaging element 260. The By repeating such imaging while moving the substrate 210 in the arrow direction, a two-dimensional image of the substrate 210 is acquired, and defect extraction is performed by appropriately performing image processing on the two-dimensional image.
Here, the image by regular reflection light is acquired when θ _i = θ _o , and the image by diffraction light is acquired when θ _i and θ _o are in a predetermined positional relationship according to the diffraction order, and the image by scattered light is obtained. Is obtained when θ _i and θ _o are set so that there is no specularly reflected light or diffracted light, for example, when θ _i is close to 90 ° and θ _o is slightly shifted from θ _i Is done. For this reason, in the configuration shown in FIG. 4, in order to acquire an image of the substrate by these specularly reflected light, diffracted light, and scattered light, three inspections are performed while changing the settings of θ _i and θ _o .
In addition to the configuration similar to the above, Patent Document 1 describes a surface defect inspection apparatus provided with a plurality of sets of an imaging optical system and a one-dimensional imaging device, which are arranged at different angular positions.
Japanese Patent No. 3668294 (FIGS. 1, 5, and 7)

However, the conventional defect inspection apparatus as described above has the following problems.
In the defect inspection apparatus as shown in FIG. 4, in order to acquire an image of the substrate by specularly reflected light, diffracted light, and scattered light, it is necessary to perform three inspections by changing the settings of θ _i and θ _o . There is a problem that time is required for angle setting and measurement, and efficient inspection cannot be performed. In particular, in the inspection of the manufacturing process, since the inspection time affects the productivity, a rapid inspection is strongly demanded.
Further, the technique described in Patent Document 1 describes a technique in which an imaging optical system and a one-dimensional imaging device are provided with a plurality of sets with different angular positions. In this case, specular reflection light is obtained by one measurement. And images of diffracted light or a plurality of diffracted lights can be acquired simultaneously. Therefore, although the inspection efficiency is slightly improved, the optical element on the object side of the imaging optical system needs to be close to the substrate, so the angle relationship that can be arranged without interfering with each other is limited, so the angle suitable for inspection There are cases where the condition cannot be set.
In addition, since a plurality of sets of imaging optical systems and one-dimensional imaging elements that are expensive and need to have high placement accuracy are provided, there is a problem that the apparatus configuration is complicated and the manufacturing cost is high.

  The present invention has been made in view of the above problems, and provides a defect inspection apparatus capable of efficiently inspecting using light from a substrate emitted in a plurality of angular directions. With the goal.

In order to solve the above-described problems, a defect inspection apparatus according to the present invention illuminates a line-shaped illumination region with respect to a mounting table on which a substrate as a subject is mounted and the substrate mounted on the mounting table. A plurality of illumination units for irradiating light, an imaging optical system for imaging light from the illumination area on the substrate, and a one-dimensional imaging for acquiring an image of the substrate imaged by the imaging optical system And a moving stage for relatively moving the substrate placed on the mounting table in a direction orthogonal to the longitudinal direction of the illumination area, and the incident angle of each illumination light from the plurality of illumination parts with respect to the illumination area An angle setting unit that sets different angles to each other, the plurality of illumination units irradiate light of different wavelengths as illumination light, and the one-dimensional imaging unit selects the light of different wavelengths, respectively. Wavelength selection means and selection by the wavelength selection means Characterized in that it is configured wavelength of light from a plurality of light receiving portions for receiving respectively.
According to this invention, the angle setting unit sets the incident angles of the illumination light from the plurality of illumination units to different angles, and the plurality of illumination units has different wavelengths with respect to the illumination region on the substrate. The incident angle of the illumination light is irradiated by the one-dimensional imaging unit that irradiates the light simultaneously, forms the light from the substrate by the illumination light by only one imaging optical system, and includes the wavelength selection unit and the plurality of light receiving units. It is possible to simultaneously acquire images for different wavelengths respectively corresponding to. A plurality of two-dimensional images of the substrate can be acquired by relatively moving the substrate in a direction orthogonal to the longitudinal direction of the illumination area by the moving stage.

  According to the defect inspection apparatus of the present invention, it is possible to simultaneously acquire images for different wavelengths corresponding to the incident angles of the illumination light. Therefore, it is possible to efficiently use the light from the substrate emitted in a plurality of angular directions. The effect that it can test | inspect automatically.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

A defect inspection apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a schematic front view showing a schematic configuration of a defect inspection apparatus according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing a schematic configuration of the control means of the defect inspection apparatus according to the embodiment of the present invention.

The defect inspection apparatus 1 according to the present embodiment irradiates a plurality of illumination lights with the substrate 21 having a periodic pattern formed on the surface as an object, and 2 on the surface of the substrate 21 according to the plurality of illumination lights. A dimensional image is acquired and the surface defect of the board | substrate 21 is test | inspected by these images.
Examples of the substrate 21 include a semiconductor wafer or a liquid crystal glass substrate having a circuit pattern formed on the surface.

  As shown in FIG. 1, the schematic configuration of the defect inspection apparatus 1 includes a moving stage 13, a first illumination unit 10, a second illumination unit 11, a third illumination unit 12, an imaging optical system 25, a one-dimensional imaging unit 27, And a control unit 60 (see FIG. 2).

  The moving stage 13 also serves as a mounting table for mounting and holding the substrate 21 and moving it in the horizontal direction in the figure. As the holding means for the substrate 21, for example, appropriate means such as vacuum suction, electrostatic suction, and clamp can be used.

The first illuminating unit 10, the second illuminating unit 11, and the third illuminating unit 12 respectively emit linear illumination lights having mutually different wavelengths, λ ₁ , λ ₂ , and λ ₃ on the substrate 21 of the moving stage 13. Irradiation is performed on a linear illumination region L extending in a direction orthogonal to the moving direction (the depth direction in the drawing). Here, the light of wavelengths λ ₁ , λ ₂ , and λ ₃ may be monochromatic light having different wavelengths, or may be light having center wavelengths of λ ₁ , λ ₂ , and λ ₃ and having a predetermined wavelength width. . In the latter case, unless otherwise specified, the entire wavelength bands are represented by the wavelengths λ ₁ , λ ₂ , and λ ₃ .
Although the values of the wavelengths λ ₁ , λ ₂ , and λ ₃ can be set as appropriate, in the present embodiment, the first illuminating unit 10, the second illuminating unit 11, and the third illuminating unit 12 are made to be specularly reflected light, Corresponding to use for observation with diffracted light and scattered light, they are set to a red wavelength region, a blue wavelength region, and a green wavelength region, respectively.

Further, the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12 are not particularly illustrated in FIG. 1, but the first illumination unit rotation mechanism 111, the second illumination unit rotation mechanism 112, and the like, respectively. The third illumination unit rotation mechanism 113 (see FIG. 2) is held so as to be rotatable about the illumination region L.
As a structure of the 1st illumination part rotation mechanism 111, the 2nd illumination part rotation mechanism 112, and the 3rd illumination part rotation mechanism 113, the rotation arm mechanism etc. which were provided so that rotation by a motor etc. was employ | adopted, for example. can do. In this case, each motor is electrically connected to the control unit 60, and the angular position of each rotation can be changed independently by the control unit 60.
Hereinafter, as shown in FIG. 1, the angular positions of the first illuminating unit 10, the second illuminating unit 11, and the third illuminating unit 12 are set in the plane along the moving direction of the moving stage 13 including the normal line of the substrate 21. The angles measured from the normal line 21 are represented as angles θ _i1 , θ _i2 , and θ _i3 , respectively.

The light source and the illumination optical system used for the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12 can have an appropriate configuration that irradiates light of each wavelength in a line shape. For example, a lamp such as a halogen lamp, a laser light source, an LED, or the like can be employed as the light source.
In the present embodiment, light from a white light source (not shown) is guided by an optical fiber whose exit ports are arranged in a line, and is made substantially parallel light by a condensing lens (not shown) on the optical path of each outgoing light. The wavelength filters 100, 101, and 102 are arranged on the illumination area L so as to irradiate light of wavelengths λ ₁ , λ ₂ , and λ ₃ onto the illumination region L.

The imaging optical system 25 uses the normal line of the substrate 21 as shown in FIG. 1 in the illumination light irradiated to the illumination region L from the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12. the light directed from the normal line of the substrate 21 in the direction of the angle theta _r in the plane along the moving direction of the movable stage 13 includes condensed, is intended for forming a reduced image of the illumination area L on the imaging surface.
In the present embodiment, a collimating lens 23 and an imaging lens 24 are disposed from the substrate 21 side, and each is integrated with the imaging unit housing 20. The collimating lens 23 and the imaging lens 24 can employ various known configurations according to the size of the illumination region L and the necessary reduction magnification.
Although not particularly shown in FIG. 1, the imaging unit housing 20 is rotatably held around the illumination area L by an imaging unit rotating mechanism 200 (see FIG. 2).
In the present embodiment, as the configuration of the imaging unit rotation mechanism 200, for example, a rotation arm mechanism that can be rotated by a motor or the like can be employed. In this case, the motor is electrically connected to the control unit 60, and the angular position of each rotation can be independently changed by the control unit 60.

As shown in FIG. 1, the one-dimensional imaging unit 27 includes dichroic mirrors 30 and 31 arranged in this order from the imaging lens 24 side on the optical axis on the image side of the imaging optical system 25. The first light receiving unit 201 is on the optical path of the reflected light, the second light receiving unit 202 is on the optical path of the light reflected by the dichroic mirror 31, and the third light receiving unit 203 is on the optical path of the light passing through the dichroic mirror 31. Are respectively arranged and fixed to the imaging unit housing 20.
Here, the substrate 21 and the light receiving surfaces of the first light receiving unit 201, the second light receiving unit 202, and the third light receiving unit 203 are positioned so as to have a conjugate relationship.

The dichroic mirror 30 has a dichroic mirror surface provided with wavelength separation characteristics that reflects light of wavelength λ ₁ and transmits light of wavelengths λ ₂ and λ ₃ .
The dichroic mirror 31 has a dichroic mirror surface provided with a wavelength separation characteristic that reflects light of wavelength λ ₂ and transmits light of wavelength λ ₃ .
For this reason, the dichroic mirrors 30 and 31 constitute wavelength selection means for selectively separating light of wavelengths λ ₁ , λ ₂ , and λ _{3 in} the one-dimensional imaging unit 27.

The first light receiving unit 201, the second light receiving unit 202, and the third light receiving unit 203 have wavelength sensitivities at least at wavelengths λ ₁ , λ ₂ , and λ ₃ , respectively, and images the light imaged on each light receiving surface. A one-dimensional imaging device that performs photoelectric conversion, for example, a one-dimensional CCD having an appropriate number of pixels.

The control unit 60 performs overall control of the defect inspection apparatus 1. As shown in FIG. 2, the measurement control unit 61, the rotation control unit 62, the movement control unit 63, the illumination control unit 64, the imaging control unit 65, An image storage unit 66, an image processing unit 67, and a defect determination unit 68 are provided.
The control unit 60 may be configured by hardware corresponding to each function, or each function by executing an appropriate control program on a computer having a CPU, a memory, an input / output interface, a storage unit, and the like. May be realized.

  The measurement control unit 61 is electrically connected to the rotation control unit 62, the movement control unit 63, the illumination control unit 64, and the imaging based on preset setting conditions or an operation input from an operation unit (not shown). Communication with the control unit 65 and the image processing unit 67 is performed to control the operation of the apparatus.

Based on the angle setting value sent from the measurement control unit 61, the rotation control unit 62 is based on the imaging unit rotation mechanism 200, the first illumination unit rotation mechanism 111, the second illumination unit rotation mechanism 112, and the third illumination. The rotation unit 113 is driven to set the angular positions of the imaging unit housing 20, the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12, and the angle setting unit together with each rotation mechanism Is configured.
In the present embodiment, the angles θ _i1 and θ _r are θ _i1 = θ so that the specularly reflected light from the substrate 21 by the illumination light having the wavelength λ ₁ from the first illumination unit 10 enters the imaging optical system 25. It is set to θ _r.
Further, the angle θ _i2 indicates that when the illumination light having the wavelength λ ₂ from the second illumination unit 11 is incident on the substrate 21, the diffracted light of a predetermined order due to the periodic pattern of the substrate 21 is in the direction of the angle θ _r . The value is set such that the light advances and enters the imaging optical system 25.
The angle θ _i3 indicates that only the scattered light on the illumination region L of the substrate 21 enters the imaging optical system 25 when the illumination light having the wavelength λ ₃ from the third illumination unit 12 is incident on the substrate 21. The angle is set so that
Note that the angles θ _i1 , θ _i2 , θ _i3 , and θ _r are set in a range in which the first illumination unit 10, the second illumination unit 11, the third illumination unit 12, and the imaging unit housing 20 do not interfere with each other. The

The movement control unit 63 is electrically connected to the movement stage 13, and controls the movement speed and movement direction of the movement stage 13 based on a movement control signal sent from the measurement control unit 61.
The illumination control unit 64 is electrically connected to each of the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12, and performs lighting on / off control of each illumination light and light amount control.
The imaging control unit 65 is electrically connected to the first light receiving unit 201, the second light receiving unit 202, and the third light receiving unit 203 of the one-dimensional imaging unit 27, and is imaged and photoelectrically converted on the plurality of light receiving units. 1-dimensional image data for each wavelength is acquired by taking in each image signal.
The one-dimensional image data for each wavelength acquired by the imaging control unit 65 is further stored in the image storage unit 66 while maintaining the order of image acquisition timing.
The image acquisition timing of the imaging control unit 65 is synchronized with the timing at which the moving stage 13 has moved by a moving amount corresponding to a certain line pixel pitch.

The image storage unit 66 stores two-dimensional image data configured by arranging the one-dimensional image data acquired by the imaging control unit 65 in the order of image acquisition timing, and image data such as defect image data processed by the image processing unit 67. To save. These image data are all stored together with the information of the light receiving unit that acquired the image.
The image storage unit 66 is electrically connected to the display unit 70 and stores the stored image data in the display unit 70 in accordance with a preset timing or an operation input from an operation unit (not shown). It can be sent and displayed.

The image processing unit 67 calls the two-dimensional image data stored in the image storage unit 66 in accordance with a control signal from the measurement control unit 61, and performs known image processing such as noise removal, luminance adjustment, and defect extraction processing. Is.
Here, the defect extraction processing is performed by well-known image processing such as, for example, taking a difference from a reference image having no defect according to the angular position of the light receiving unit from which the image is acquired. The image data after the defect extraction process is sent to the defect determination unit 68.

  The defect determination unit 68 performs feature extraction of the defect image extracted by the image processing unit 67, and calculates, for example, the defect type and the size of the defect with reference to defect image data stored in a defect dictionary or the like. Then, inspection results such as the presence / absence of a defect and acceptance / rejection of the substrate 21 are displayed on the display unit 70 as image information or character information.

Next, the operation of the defect inspection apparatus 1 will be described focusing on the image acquisition operation.
The measurement control unit 61 performs initial setting of inspection conditions in accordance with a condition setting list stored in advance for each inspection substrate. Examples of the inspection conditions include angle setting of each illumination unit and the imaging optical system 25, light amount setting, and the like.

For example, defects such as film thickness unevenness are inspected by observing an image using regular reflection light. Therefore, the measurement control unit 61 refers to a previously stored data table or the like, selects the optimum angle θ _r for observing the film thickness unevenness from the conditions such as the manufacturing process of the substrate 21, and the first A control signal for setting the angular position of the illuminating unit 10 to be θ _i1 = θ _r is sent to the rotation control unit 62.
Then, the rotation control unit 62 rotates the imaging unit rotation mechanism 200 and the first illumination unit rotation mechanism 111 to move the respective angular positions of the first illumination unit 10 and the imaging unit housing 20 to the set values. To do.

For example, a circuit pattern defect or the like is inspected by observing an image using diffracted light. Therefore, the measurement control unit 61 refers to a data table stored in advance, and selects the emission direction of the diffracted light of the optimum diffraction order for observing a defect in the circuit pattern from information such as the circuit pattern pitch. Then, a control signal for setting an angle θ _i2 for making the optical axis direction of the imaging optical system 25 coincide with this is sent to the rotation control unit 62.
And the rotation control part 62 rotates the 2nd illumination part rotation mechanism 112, and moves the angular position of the 2nd illumination part 11 to a setting value.
The emission direction of the diffracted light from the substrate 21 is determined by the wavelength λ _{2 of the} illumination light, the pitch p of the circuit pattern, and the diffraction order, but in recent years, the circuit pattern has become highly refined and the angle θ _{i2 with} respect to a certain wavelength. The value of tends to be a larger value. Therefore, in the present embodiment, the angle θ _i2 is set to be smaller by setting the wavelength λ ₂ to the blue wavelength region on the short wavelength side. Thereby, even when the pitch p of the circuit pattern is small, the incident angle of the second illumination unit 11 can be set relatively shallow, and the arrangement is made so as not to interfere with other illumination units, the imaging unit housing 20, and the like. be able to.

For example, defects such as dust adhesion and scratches are inspected by observing an image using scattered light. Therefore, the measurement control unit 61 rotates a control signal for setting θ _i3 to an angle at which only the image of the scattered light of the illumination light from the third illumination unit 12 is imaged by the imaging optical system 25. It sends out to the control part 62, rotates the 3rd illumination part rotation mechanism 113, and moves the angle position of the 3rd illumination part 12 to a setting value.

The measurement control unit 61 sets the amount of each illumination light to the illumination control unit 64, and the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12 are turned on by the illumination control unit 64. To do.
In this case, the light quantity of each illumination light is set so that the reflected light from the substrate of each illumination light has almost the same brightness.
In particular, each reflected light of the present embodiment is specularly reflected light, diffracted light, and scattered light from the substrate, and the ratio of the amount of light that can reach the imaging optical system 25 differs from the amount of emitted light of the illumination light. It is preferable to set the light amount of each illumination unit so that the light amount incident on the imaging optical system 25 is substantially the same. As a result, the amount of light reaching the first light receiving unit 201, the second light receiving unit 202, and the third light receiving unit 203 is substantially the same, and each two-dimensional image acquired from each of them is an appropriate one that is not blacked out or overexposed. A luminance value can be taken, and an inspection using each two-dimensional image can be performed with high accuracy.

In the present embodiment, the illumination light from the first illumination unit 10, the second illumination unit 11, and the third illumination unit 12 is incident on the imaging optical system 25 as specularly reflected light, diffracted light, and scattered light, respectively. When set to the same amount of illumination light, the amount of light incident on the imaging optical system 25 is expected to decrease in this order. Therefore, the wavelength λ ₃ of the third illumination unit 12 with the least amount of light incident on the imaging optical system 25 is set to a wavelength with high light receiving sensitivity of the light receiving unit, and the amount of light incident on the imaging optical system 25 is the largest. it is preferable to set the wavelength lambda ₁ of the first illumination unit 10 to the wavelength light reception sensitivity is low of the light receiving portion.

  When the initial setting of the inspection conditions is completed as described above, the measurement control unit 61 starts the inspection. That is, the movement control unit 63 moves the moving stage 13 at a constant speed in a fixed direction, and the imaging control unit 65 acquires an image from the one-dimensional imaging unit 27 at a timing corresponding to one pixel pitch in the movement direction.

Light emitted from the first illuminating unit 10, the second illuminating unit 11, and the third illuminating unit 12 is transmitted through the respective wavelength filters 100, 101, and 102, so that the wavelengths λ ₁ , λ ₂ , and λ ₃ are abbreviated. As illumination light composed of parallel light beams, the illumination light is superimposed on the illumination area L and irradiated.
Light from the first illumination unit 10 is regularly reflected by the substrate 21 advances in the direction of the angle theta _r, is incident on the imaging optical system 25.
Light from the second illumination unit 11 is diffracted by the circuit pattern on the substrate 21, a predetermined order diffracted light proceeds to an angle theta _r direction is incident on the imaging optical system 25.
Light from the third illumination unit 12 is scattered by dust attached to the substrate 21 or scratches on the substrate 21, and scattered light in the range of NA of the imaging optical system 25 enters the imaging optical system 25. .

The light that has entered the imaging optical system 25 is condensed by the collimating lens 23 and the imaging lens 24, is incident on the one-dimensional imaging unit 27, and is simultaneously imaged at the position of the light receiving surface conjugate with the illumination region L. .
That is, the light of wavelength λ ₁ is reflected by the dichroic mirror 30 and imaged on the first light receiving unit 201. The light having the wavelength λ ₂ passes through the dichroic mirror 30, is reflected by the dichroic mirror 31, and forms an image on the second light receiving unit 202. The light having the wavelength λ ₃ passes through the dichroic mirrors 30 and 31 and forms an image on the third light receiving unit 203.

The first light receiving unit 201, the second light receiving unit 202, and the third light receiving unit 203 photoelectrically convert each wavelength light, and send it to the imaging control unit 65 as an image signal.
When each image signal is captured, the imaging control unit 65 stores the respective light receiving units in the image storage unit 66 in a state where the respective light receiving units and the image acquisition positions are identified.
By repeating the above, one-dimensional image data is accumulated along the moving direction on the substrate 21. When the relative movement of the illumination area L over the entire inspection area of the substrate 21 is completed, the movement control unit 63 stops the movement stage 13.

Next, defect extraction processing and defect determination processing are performed based on the acquired two-dimensional image data.
In the defect extraction processing, each two-dimensional image data stored in the image storage unit 66 according to each light receiving unit is sequentially called to the image processing unit 67, and the image processing unit 67 performs defect extraction processing according to the observation image. .
The defect determination unit 68 calculates a defect type, a defect size, and the like from the image data after defect extraction sent from the image processing unit 67 and displays the defect determination result on the display unit 70.
Thus, the defect inspection of one substrate 21 is completed.
If there is another substrate 21 to be inspected, it is placed on the moving stage 13 in place of the substrate 21, and the above is repeated until all the substrates 21 have been inspected.

As described above, according to the defect inspection apparatus 1, three two-dimensional patterns corresponding to illumination light having three types of incident angles are obtained while the illumination region L is relatively moved on the substrate 21 and one scan is performed. Images are separated by wavelength and acquired simultaneously. Therefore, image data for inspection can be acquired quickly and efficiently.
Further, the optical system on the one-dimensional imaging unit side can perform imaging using only the imaging optical system 25 in which one angle with respect to the substrate 21 is fixed. Therefore, for example, an apparatus having a simple configuration can be obtained as compared with a conventional configuration in which a single light source is used and different imaging optical systems and one-dimensional imaging elements are arranged in a plurality of different emission directions.
In addition, the plurality of illumination units need only be able to illuminate the range of the illumination region L at a predetermined angle, and positioning in the optical axis direction and the like may be performed with lower accuracy than the imaging optical system 25. The labor required is reduced compared with the case where the imaging optical system is positioned, and each rotation mechanism that rotates the illumination unit can also have a simple configuration.

Next, a modification of this embodiment will be described.
FIG. 3A is a front view of a one-dimensional imaging unit used in a defect inspection apparatus according to a modification of the embodiment of the present invention. FIG. 3B is a schematic cross-sectional view along the sensor arrangement direction of the color line sensor used in the defect inspection apparatus according to the modification of the embodiment of the present invention.

This modification includes a one-dimensional imaging unit 270 in place of the one-dimensional imaging unit 27 in the defect inspection apparatus 1 of the above embodiment.
The one-dimensional imaging unit 270 includes a color line sensor 204 disposed on the optical path of the light emitted from the imaging optical system 25, as shown in FIG.
In the color line sensor 204, as shown in FIG. 3B, a light receiving surface is formed on a circuit board 204a, and a large number of light receiving portions 204b that perform photoelectric conversion are linearly arranged. The incident side of the light receiving portion 204b, a red wavelength region, green wavelength region is the wavelength filter F _r, F _g, a wavelength selecting means F _b are arranged one by one in order to transmit light in the blue wavelength region A filter unit 204c is provided. Each of these three light receiving parts 204b constitutes one pixel P for reading.
The light receiving surface of the color line sensor 204 formed by these light receiving portions 204b is arranged in a conjugate relationship with the illumination region L in the depth direction of the paper surface of FIG.

According to this structure, the first illumination unit 10, the second illumination unit 11, the illumination light irradiated from the third illuminating unit 12, regular reflected light from the substrate 21, the diffracted light, the angle theta _r direction as scattered light The light traveling to the center of the color line sensor 204 is linearly imaged through the imaging optical system 25 on the light receiving unit 204b.
At this time, the light reaching one pixel P is transmitted with light having wavelengths λ ₁ , λ ₂ , and λ ₃ by the wavelength filters F _r , F _g , and F _b that are wavelength selection means, respectively. The images are formed on the different light receiving portions 204b.
The luminance information of each light receiving unit 204b is separated into three image signals corresponding to each wavelength filter and sent to the imaging control unit 65. Therefore, the imaging control unit 65 simultaneously acquires image signals corresponding to the three one-dimensional images corresponding to the wavelengths λ ₁ , λ ₂ , and λ ₃ .
Subsequent image processing, defect extraction processing, and defect determination processing are performed in the same manner as in the above embodiment. However, in this modification, the light receiving position in one pixel P is shifted by 1/3 pixel depending on the wavelength, and therefore, a positional accuracy of 1/3 pixel or less is required for calculation processing or image display. First, a process for correcting the position coordinates of the image data corresponding to each wavelength is performed.

  According to this modification, since the color line sensor is used as the one-dimensional imaging unit, a compact configuration can be achieved.

  In the above description, the example in which three illumination units are provided is described. However, the number of illumination units is not particularly limited, and may be an appropriate number of 2 or more as necessary. be able to.

In the above description, the angle setting unit sets the incident angle of the plurality of illumination units and the relative position with respect to the angular position of the imaging optical system, and allows the specular reflected light, diffracted light, and scattered light to enter the imaging optical system. As described in the example, the light incident on the imaging optical system may be combined in any way depending on the necessary observation mode.
For example, any of them may be omitted. Further, it is also possible to acquire an image using a plurality of orders of diffracted light by changing the incident angle and the wavelength of illumination light. Acquiring an image using a plurality of orders of diffracted light is advantageous because, for example, even when a complex circuit pattern having a plurality of pitches is used, circuit patterns corresponding to each pitch can be inspected simultaneously.

In the above description, the example in which the wavelengths of the illumination light from the plurality of illumination units are fixed has been described. However, the illumination control unit may be configured to change the wavelength of each illumination unit. For example, it is possible to adopt a configuration in which a plurality of wavelength filters having different transmission wavelengths are provided so as to be switchable, so that the wavelength light to be transmitted and the wavelength band can be selected, or a plurality of light sources having different wavelengths can be switched.
According to such a configuration, for example, when using diffracted light, the direction of the diffracted light that changes depending on the circuit pattern can be changed by wavelength switching together with the angle position of the illuminating unit. It becomes easy to narrow the variable range of the position and set the incident angle to a small range. In particular, if the incident light of the illumination light can be set to be small, it is advantageous in that a decrease in resolution due to oblique incidence can be prevented.
Thus, when changing the wavelength of illumination light, it is preferable to change a wavelength within the range which can be selected with a wavelength selection means. In this case, it is not necessary to change the wavelength selection means, so that a simple configuration can be achieved.

  In the above description, the moving stage has been described as an example of the case where the moving stage also serves as a substrate mounting table. However, if the moving stage can relatively move the substrate mounted on the mounting table in a direction perpendicular to the longitudinal direction of the illumination area. Therefore, the substrate may be mounted on a mounting table whose position is fixed, and the illumination unit and the imaging optical system may be moved by the moving stage.

In the above description, an example in which a plurality of illumination units, an imaging optical system, and a one-dimensional imaging unit can change their respective angular positions by the angle setting unit has been described. If you do not need to change the angular position even if the subject changes, such as when observing using light or when the reflection angle of specularly reflected light can be fixed, the setting of the angular position may be fixed. Good.
In the above description, the angle setting unit has been described as an example in which the angle position is automatically set by the rotation control unit 62. However, the angle setting unit may be configured to manually switch the angle position.

  In the above description, an example in which a plurality of dichroic mirrors or a plurality of wavelength filters are used as the wavelength selection unit has been described. However, the wavelength selection unit is not limited to these, for example, a dichroic prism or the like. May be used.

  In the above description of the modification, an example in which a one-line type color line sensor is used as the color line sensor has been described. However, light receiving units corresponding to the respective colors are arranged in a plurality of lines in one pixel. Another type of color line sensor may be used.

In the above description, the illumination light with different wavelengths is simultaneously received by the plurality of light receiving units, and the example is described in which the images from the light emitted from the substrate emitted in the plurality of angular directions are simultaneously acquired. For example, using a single light receiving unit, a plurality of wavelength lights incident on the light receiving unit are incident in a time-sharing manner during one line of imaging timing, thereby acquiring a plurality of images while scanning the substrate once. You may make it do. For example, a configuration in which a plurality of wavelength filters are sequentially switched in the optical path between the imaging optical system and the light receiving unit so as to acquire a one-line image, and the like.
According to such a configuration, although the measurement time is longer than in the case where a plurality of images are acquired at the same time, the angle condition of the illumination unit or the like can be fixed and the inspection can be performed in one scan. There is no need to change the angle or return the substrate position to the initial position. Therefore, the measurement time can be reduced as compared with a conventional defect inspection apparatus that performs a plurality of measurements by changing the angle setting.

It is a typical front view which shows schematic structure of the defect inspection apparatus which concerns on embodiment of this invention. It is a functional block diagram which shows schematic structure of the control means of the defect inspection apparatus which concerns on embodiment of this invention. It is a front view of the one-dimensional imaging part used for the defect inspection apparatus which concerns on the modification of embodiment of this invention, and typical sectional drawing in alignment with the sensor arrangement direction of the color line sensor used for it. It is a perspective view which shows schematic structure of the defect inspection apparatus which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 1st illumination part (illumination part)
11 2nd illumination part (illumination part)
12 3rd illumination part (illumination part)
13 Moving stage 21 Substrate (subject)
25 Imaging optical system 27, 270 One-dimensional imaging unit 30, 31 Dichroic mirror (wavelength selection means)
101, 102, 103 Wavelength filter 201 First light receiving part (light receiving part)
202 2nd light-receiving part (light-receiving part)
203 3rd light-receiving part (light-receiving part)
204 Color line sensor 204b Light receiving unit 204c Filter unit (wavelength selection means)
F _r R filter F _g G filter F _b B filter P Pixel 60 Control unit 200 Imaging unit rotation mechanism (angle setting means)
111 1st illumination part rotation mechanism (angle setting means)
112 2nd illumination part rotation mechanism (angle setting means)
113 3rd illumination part rotation mechanism (angle setting means)
61 Measurement control unit 62 Rotation control unit (angle setting means)
64 Lighting control unit

Claims (3)

A mounting table for mounting a substrate as a subject;
A plurality of illumination units that irradiate illumination light to a linear illumination region with respect to the substrate placed on the mounting table;
An imaging optical system for imaging light from the illumination region on the substrate;
A one-dimensional imaging unit for acquiring an image of the substrate imaged by the imaging optical system;
A moving stage for relatively moving the substrate mounted on the mounting table in a direction orthogonal to the longitudinal direction of the illumination area;
An angle setting unit for setting the incident angles of the illumination lights from the plurality of illumination units to the illumination area to be different from each other;
The plurality of illumination units irradiate light having different wavelengths as illumination light,
The one-dimensional imaging unit includes a wavelength selection unit that selects the light beams having different wavelengths, and a plurality of light receiving units that respectively receive the light beams having wavelengths selected by the wavelength selection unit. Defect inspection equipment. The one-dimensional imaging unit is
The defect inspection apparatus according to claim 1, comprising a color line sensor in which a color filter is disposed as the wavelength selection unit on a one-dimensional imaging device having the plurality of light receiving units. The plurality of illumination units are composed of three or more illumination units,
The angle setting unit is
One of the plurality of illumination units is set at an angle so that specularly reflected light from the substrate by illumination light from the illumination unit is incident on the imaging optical system,
The other one of the plurality of illumination units is set to an angle so that diffracted light from the substrate by illumination light from the illumination unit is incident on the imaging optical system,
The other one of the plurality of illuminating units sets an angle so that scattered light from the substrate by illumination light from the illuminating unit is incident on the imaging optical system. 2. The defect inspection apparatus according to 2.

Images